Oil booms or barriers are in general use today for containing oil slicks floating on water. They usually consist of elongated structures with a floatation collar and a depending skirt which blocks passage of oil underneath the collar.
Increasingly, local laws and regulations are requiring the use of oil booms in conjunction with the loading or offloading of petroleum carrying vessels whether or not a spill has taken place. When an oil spill has occurred, or there is a present danger of one occurring from a vessel, Federal law requires that booms or other containment means be used around the vessel.
When oil booms are used in conjunction with vessels, two major problems are encountered. First, to be effective in containing oil discharged from a vessel, a boom must be held away from the hull of a vessel since a discharge from either above or below the waterline of the vessel will enter the plane of the water surface several feet away from the hull depending on the current and wind direction and velocity. The greater the distance of spacing of the boom, the better the likelihood of safe containment under most conditions. A distance of 10 feet, for example, should handle most expected conditions. When influenced by wind and/or current, an unrestrained oil boom will tend to cling to the vessel's hull, at least along a portion of the waterline thereof. Breasting the boom away from the vessel hull is now a legal requirement in some localities. A second important problem involving vessels in conjunction with oil booms occurs when the vessel involved is a steamship. For technical reasons related to the ship's power plant, steamships must keep their propellers turning constantly to remain in a condition to get underway. This is accomplished, when the ship is moored or at anchor, by means of "jacking gear" which slowly jacks the propeller shaft over to maintain the required rotation. When steamships are to be "boomed off" it is imperative that the boom be kept away from the wheel otherwise it will be caught up by the slowly rotating propeller and destroyed with an attendant possibility of damage to the ship's propulsion gear. The above problems are dealt with at present by anchoring segments of the boom away from the hull and propeller of the boomed off vessel to provide the required spacing. The forces generated by current and wave forces on oil boom restraints can be quite large rendering anchors unreliable unless large, sophisticated anchoring systems are used. Anchoring systems are also vulnerable to marine traffic which is generally quite heavy and closely confined in many harbors where fuel and cargo transfer operations take place. Conventional fending devices such as camels, where available, tend to be quite heavy and difficult to maneuver, particularly with the small boats normally used to tend boom. Camels are also quite expensive if they are to be maintained solely for the purpose of oil boom handling and would have to be quite large to stand a boom away from a propeller which may be as much as 15 feet in radius.